The present invention relates to a cooking appliance of a food product, which comprises a pair of plates made of thermally conductive material heated electrically and articulated to one another, each of these plates having a cooking surface, the two cooking surfaces being able to be brought together by folding one plate against the other to cook a food product clamped between said plates. The invention has been designed for making an electric waffle iron, especially for professional use. But it may have various other applications, for cooking a range of products.
A traditional electric waffle iron for professional use comprises cast-iron cooking plates, known as “irons”, of a generally rectangular shape, whereof the cooking surface has one or more impressions composed of studs in relief and cavities for giving the waffle the preferred configuration. In some models, these plates can be pivoted relative to one another at a flat angle, at 180°, the two cooking plates then being located in a common horizontal plane. In other models, at “90°”, pivoting a plate is done only at a little over a right angle, and the dough is deposited onto the other cooking plate, remaining horizontal. Some appliances are also designed to be able to be returned to the closed state at an angle of 180°, such that the dough can be allocated correctly in the space separating the two plates; this is useful especially for cooking relatively fluid doughs.
In general, the waffle iron comprises a fixed base, or chassis, for example made of stainless steel, on which said plates are mounted and/or articulated. This base can correspond such that each of said plates can be folded back flat on the latter, singly and/or together with the other plate, so as to be supported against said base in a horizontal position by its dorsal face. In other models, a housing containing the electric power and thermal setting is solid with one of the plates; it is connected electrically to each of the heating plates, either directly or by means of a flexible cable which enables free pivoting when the plate in question is opened.
The present invention is applicable to these different models. In known appliances of this kind, the so-called dorsal face, opposite the cooking surface of each of the plates, exhibits a depression (recess) with a flat base of extended surface, inside which is mounted an electric heating resistor. This is generally a flat thin strip made of conductive metal (nickel-chrome, alloy for example) deposited on a thin plate of insulating electric material, usually based on mica. This plate can be interposed between two similar thin insulating plates. It is this multilayer structure which is inserted into the abovementioned depression.
This structure also accommodates a flexible fitting made of thermal insulating material, which covers the mica-based heating structure. The opening of the depression is generally blocked by a closing plate made of sheet metal, fixed by means of screws to the back of the iron. This plate lightly compresses the layer of insulating material for the purpose of applying said multilayer structure with a certain degree of tightness against the wall of the iron to ensure proper heat transfer.
An appliance of this genre has some disadvantages. In use, hot oil or other hot fatty bodies used for applying liquid to the overcooking surfaces have a tendency to infiltrate to the back of the plates and corrode the multilayer structure and the electric resistor, which alters the insulating qualities of the structure and, over time, causes short-circuits. Fatty bodies also impregnate the layer of thermally insulating insert, resulting in its being crushed and deformed over time, such that it loses its insulation capacity and the heating structure is no longer applied correctly or evenly to the back of the iron. Thermal transfer is now poor. Also, dough (more or less liquid) infiltrates the gap between the peripheral edge of the closing plate and the rim of the depression, and this gap can become clogged by dough crust, which is hardly satisfactory in terms of hygiene.
The aim of the present invention is to rectify these difficulties. For this purpose and in keeping with the invention, a heating module of form complementary to that of said depression is fitted and fixed removably inside the latter, this module being provided with a shielded electric resistor for heating said plate when it is supplied with electric current. A shielded electric resistor comprises an electric wire of high resistance, which is embedded in dielectric but thermally conductive insulating material, the whole being housed in a protective tubular sheath, ensuring its tightness.
Due to the removable character of this heating module, it is easy to remove it periodically from the depression, giving free access to the entire dorsal face of the iron, including the depression, which allows for convenient cleaning. The reliability and shelf life of such an appliance are considerably greater relative to those of traditional appliances.
According to other advantageous and non-limiting characteristics of the invention:                said module has the form of a flat cassette, of minimal thickness;        said module has a “sandwich” structure comprising, from the base of the depression to the exterior:        a heat-distribution sheet made of material having good thermal conductivity, for example aluminium;        said shielded electric resistor;        a plating sheet of resistance against the sheet heat-distribution sheet;        a plate of thermally insulating material;        a closing sheet; these different components being assembled with each other detachably, for example by means of screws;        said plate made of thermally insulating material has a calibrated and constant thickness        the appliance comprises a base on which said plates are mounted and articulated about an axis which coincides with their mutual axis of articulation;        this base corresponds such that each of the plates can be folded back flat on the latter, singly and/or together with the other plate, so as to be supported against said base by its dorsal face, in a horizontal position;        the base is provided with control and adjustment means of the electric feed of the resistors of each of the plates, these means being connected to each of said modules by flexible cabling which hinders neither pivoting of the plates nor removal of the modules from their depression;        at least one module is fitted with a temperature probe able to be housed in a receiving groove of complementary form arranged in the base of said depression when the module is fitted in the latter and fixed to the cooking plate;        each of the modules is fixed to the cooking plate by means of screws and is applied with a certain degree of tightness against the base of the depression.        
Such an appliance is advantageously intended for cooking flour-based baking dough for making waffles, the cooking surfaces of the plates being provided with impressions adapted for this purpose. Various applications are feasible, for example for cooking slices of meat or fish. Other characteristics and advantages of the invention will emerge from the following description of one possible embodiment of the invention.